Organic Light Emitting Device and Display Apparatus

ABSTRACT

An organic light emitting device and a display apparatus are provided. The organic light emitting device includes an anode, a cathode and a light-emitting layer arranged between the anode and the cathode, wherein a doped structure layer is arranged between the anode and the light-emitting layer, the doped structure layer comprises a host material and a guest material doped in the host material, and the host material and the guest material satisfy:−1.5eV&lt;|LUMO(A)|−|HOMO(B)|&lt;1.5eV;LUMO(A) is the lowest unoccupied molecular orbit (LUMO) energy level of the host material, and HOMO(B) is the highest occupied molecular orbit (HOMO) energy level of the guest material.

TECHNICAL FIELD

The present disclosure relates to, but is not limited to, the technicalfield of display, in particular to an organic light emitting device anda display apparatus.

BACKGROUND

Organic Light Emitting Device (OLED) is an active light-emitting device,which has the advantages of light emission, ultra-thin, wide viewingangle, high brightness, high contrast, low power consumption, highreaction speed and so on, and has gradually become the next generationdisplay technology with great development prospects.

OLED includes an anode, a cathode and a light-emitting layer arrangedbetween the anode and the cathode. Its light-emitting principle is thatholes and electrons are injected into the light-emitting layer from theanode and the cathode respectively. When the electrons and holes meet inthe light-emitting layer, the electrons and holes recombine to generateexcitons, and these excitons emit light while changing from excitedstate to ground state. In order to inject electrons and holes smoothlyfrom the electrode to the light-emitting layer at a lower drivingvoltage, a hole injection layer and a hole transport layer are arrangedbetween the anode and the light-emitting layer, and an electroninjection layer and an electron transport layer are arranged between thecathode and the light-emitting layer. In order to make OLED achievebetter light-emitting efficiency and realize low voltage and long life,the design of the hole injection layer is more important.

SUMMARY

The following is a summary of subject matter described in detail herein.This summary is not intended to limit the protection scope of theclaims.

An organic light emitting device includes an anode, a cathode and alight-emitting layer arranged between the anode and the cathode, whereina doped structure layer is arranged between the anode and thelight-emitting layer, the doped structure layer includes a host materialand a guest material doped in the host material, and the host materialand the guest material satisfy:

−1.5eV<|LUMO(A)|−|HOMO(B)|<1.5eV.

LUMO(A) is the lowest unoccupied molecular orbit of the host material,and HOMO(B) is the highest occupied molecular orbit of the guestmaterial.

In an exemplary embodiment, the guest material further satisfies:

5eV≤|HOMO(B)|≤6.5eV.

In an exemplary embodiment, the host material further satisfies:

|HOMO(A)|≥6eV,|LUMO(A)|≥4eV.

HOMO(A) is the highest occupied molecular orbit (HOMO) energy level ofthe host material.

In an exemplary embodiment, a doping ratio of the guest material to thedoped structure layer is 0.1% to 40%.

In an exemplary embodiment, one of the host material and the guestmaterial includes a ketone compound and the other includes an aromaticamine compound.

In an exemplary embodiment, the guest material includes, but is notlimited to, a compound having a structure of formula (I):

In formula (I), Ar₁ to Ar₄ are each independently a substituted orunsubstituted aryl group having 5 to 50 ring atoms, L is a connectinggroup formed by a substituted or unsubstituted arylene group having 5 to50 ring atoms, or a connecting group obtained by connecting a pluralityof substituted or unsubstituted arylene groups having 5 to 50 ring atomswith M1, wherein M1 is any one of single bond, oxygen atom, sulfur atom,nitrogen atom, and saturated or unsaturated divalent aliphatichydrocarbon group having 1 to 20 carbon atoms.

In an exemplary embodiment, at least one of Ar₁ to Ar₄ is selected fromany one of the following structures:

R1 to R25 are each independently any one of hydrogen atom, aryl grouphaving 5 to 50 ring atoms, substituted or unsubstituted alkyl grouphaving 1 to 50 carbon atoms, substituted or unsubstituted alkoxy grouphaving 1 to 50 carbon atoms, substituted or unsubstituted aralkyl grouphaving 6 to 50 ring atoms, substituted or unsubstituted aryloxy grouphaving 5 to 50 ring atoms, substituted or unsubstituted arylthio grouphaving 5 to 50 ring atoms, substituted or unsubstituted alkoxycarbonylgroup having 1 to 50 carbon atoms, and aryl group having 5 to 50 ringatoms substituted by M2, wherein M2 is amino, halogen atom, cyano,nitro, hydroxyl or carboxyl.

In an exemplary embodiment, the host material includes, but is notlimited to, a compound having a structure of formula (II):

In formula (II), Z is a substituted or unsubstituted benzene ring,pyridine ring, thiophene ring, quinoline, indole or thienothiophenering.

Ar₅ is

Ar₆ is

Y₁ to Y₄ are each independently N or C-R35.

R31 to R35 are each independently selected from any one of hydrogen,deuterium, halogen group, nitrile group, substituted or unsubstitutedalkyl group, substituted or unsubstituted haloalkyl group, substitutedor unsubstituted alkoxy group, substituted or unsubstituted haloalkoxygroup, substituted or unsubstituted aryl group, substituted orunsubstituted halogenated aryl group, substituted or unsubstituted silylgroup and substituted or unsubstituted heterocycle.

X1 and X2 are each independently selected from any one of the followingstructures:

R41 to R43 are each independently any one of hydrogen, fluoroalkyl,alkyl, aryl and heterocyclic group, and R42 and R43 form a ring.

In an exemplary embodiment, the doped structure layer includes a holeinjection layer.

In an exemplary embodiment, a doping ratio of the guest material to thehole injection layer is 0.5% to 30%.

In an exemplary embodiment, the hole injection layer has a thickness of1 nm to 10 nm.

In an exemplary embodiment, at least one organic layer is furtherarranged between the hole injection layer and the light-emitting layer,a carrier mobility in the at least one organic layer is 10⁻³ cm²/Vs to10⁻⁵ cm²/Vs, and/or a conductivity of the at least one organic layer isless than or equal to that of the hole injection layer.

In an exemplary embodiment, the material of the at least one organiclayer is the same as that of the guest material.

In an exemplary embodiment, the at least one organic layer is a holetransport layer, and a material of the hole transport layer satisfies:

5eV≤|HOMO(D)|≤6.5eV.

HOMO(D) is the highest occupied molecular orbit (HOMO) energy level ofthe hole transport layer.

In an exemplary embodiment, two organic layers are further arrangedbetween the hole injection layer and the light-emitting layer, a carriermobility in the two organic layers is 10⁻³ cm²/Vs to 10⁻⁵ cm²/Vs, and/ora conductivity of the two organic layers is less than or equal to thatof the hole injection layer.

A display apparatus includes the aforementioned organic light emittingdevice.

In an exemplary embodiment, the display apparatus includes a substrateand a plurality of sub-pixels formed on the substrate, and thesub-pixels include the organic light emitting device. An orthographicprojection of the hole injection layer on the substrate overlaps with anorthographic projection of a light-emitting area of at least twosub-pixels on the substrate.

In an exemplary embodiment, an area of the hole injection layer islarger than that of the light-emitting layer.

In an exemplary embodiment, the sub-pixel further includes a pixeldriving circuit. An orthographic projection of the light-emitting layerof at least part of the sub-pixels on the substrate overlaps with anorthographic projection of a driving transistor of the pixel drivingcircuit on the substrate.

Other aspects will become apparent upon reading and understandingaccompanying drawings and the detailed description.

BRIEF DESCRIPTION OF DRAWINGS

The attached drawings are used to provide a further understanding of thetechnical scheme of the present disclosure, and constitute a part of thespecification. They are used together with the embodiments of thepresent application to explain the technical scheme of the presentdisclosure, and do not constitute a restriction on the technical schemeof the present disclosure. Shapes and sizes of the components in thedrawings do not reflect true proportions and only to be used toschematically illustrate contents of the present disclosure.

FIG. 1 is a schematic structural diagram of an OLED display apparatus;

FIG. 2 is a schematic plan view of a display area of a displaysubstrate;

FIG. 3 is a schematic sectional view of a display substrate;

FIG. 4 is an equivalent circuit diagram of a pixel driving circuit;

FIG. 5 is a schematic diagram of an OLED structure according to anexemplary embodiment of the present disclosure;

FIG. 6 is an SEM image of an evaporation film layer of a hole injectionlayer with an undoped structure; and

FIG. 7 is an SEM image of an evaporation film layer of a hole injectionlayer according to an exemplary embodiment of the present disclosure.

REFERENCE SIGNS

-   10-anode; 20-hole injection layer; 30-hole transport layer;-   40-electron block layer; 50-light-emitting layer; 60-hole block    layer;-   70-electron transport layer; 80-electron injection layer;    90-cathode;-   101-substrate; 102-driving circuit layer; 103-light-emitting device;-   104-encapsulation layer; 201-first insulating layer; 202-second    insulating layer;-   203-third insulating layer; 204-fourth insulating layer; 205-flat    layer;-   210-driving transistor; 211-storage capacitor; 301-anode;-   303-organic light-emitting-   302-pixel defining layer; 304-cathode; layer;-   402-second encapsulation-   401-first encapsulation layer; 403-third encapsulation layer. layer;

DETAILED DESCRIPTION

The embodiments herein may be implemented in a number of different ways.A person of ordinary skills in the art will readily understand the factthat implementations and contents may be transformed into a variety offorms without departing from the spirit and scope of the presentdisclosure. Therefore, the present disclosure should not be construed asbeing limited only to what is described in the following embodiments.The embodiments and features in the embodiments in the presentdisclosure may be combined randomly if there is no conflict.

In the drawings, a size of a constituent element, a thickness of a layeror an area of the layer may be sometimes exaggerated for clarity.Therefore, any implementation mode of the present disclosure is notnecessarily limited to a size shown in the drawings, and the shapes andsizes of the components in the drawings do not reflect true proportions.In addition, the drawings schematically show ideal examples, and anyimplementation mode of the present disclosure is not limited to theshapes or values shown in the drawings.

In the present disclosure, the “first”, “second”, “third” and otherordinal numbers are used to avoid confusion of constituent elements, butnot to limit in quantity.

In the present disclosure, for sake of convenience, wordings such as“central”, “upper”, “lower”, “front”, “rear”, “vertical”, “horizontal”,“top”, “bottom”, “inner”, “outer” and the like describe the orientationsor positional relations of constituent elements with reference to thedrawings, which are only for ease of description of this specificationand for simplification of the description, rather than indicating orimplying that the apparatus or element referred to must have a specificorientation, or must be constructed and operated in a particularorientation, and therefore cannot be construed as limitations on thepresent disclosure. The positional relations of the constituent elementsmay be appropriately changed according to the direction in which eachconstituent element is described. Therefore, they are not limited to thewordings in the present disclosure, and may be replaced appropriatelyaccording to the situations.

In the present disclosure, the terms “installed”, “connected” and“coupled” shall be broadly understood unless otherwise explicitlyspecified and defined. For example, a connection may be a fixedconnection, or may be a detachable connection, or an integratedconnection; it may be a mechanical connection, or may be an electricalconnection; it may be a direct connection, or may be an indirectconnection through middleware, or may be an internal connection betweentwo elements. Those of ordinary skills in the art can understand thespecific meanings of the above mentioned terms in the present disclosureaccording to specific context.

In the present disclosure, a transistor refers to an element thatincludes at least three terminals: a gate electrode, a drain electrode,and a source electrode. The transistor has a channel region between thedrain electrode (or referred to as a drain electrode terminal, a drainregion or a drain electrode) and the source electrode (or referred to asa source electrode terminal, a source region or a source electrode), anda current can flow through the drain electrode, the channel region andthe source electrode. In the present disclosure, the channel regionrefers to a region through which a current mainly flows.

In the present disclosure, the first electrode may be a drain electrodeand the second electrode may be a source electrode, or the firstelectrode may be a source electrode and the second electrode may be adrain electrode. In a situation where transistors with oppositepolarities are used or a current direction is changed in an operation ofa circuit, a function of the “source electrode” and a function of the“drain electrode” can sometimes be interchangeable. Therefore, the“source electrode” and the “drain electrode” can be interchangeable inthe present disclosure.

In the present disclosure, an “electrical connection” includes a casewhere constituent elements are connected via an element having a certainelectrical action. The “element having a certain electrical action” isnot particularly limited as long as it can transmit and receiveelectrical signals between connected constituent elements. An “elementwith a certain electrical action” may be, for example, an electrode orwiring, a switching element such as a transistor, or other functionalelements such as a resistor, an inductor or a capacitor, etc.

Herein, “parallel” refers to a state in which two straight lines form anangle of −10 degrees or more and 10 degrees or less, and thus alsoincludes a state in which the angle is −5 degrees or more and 5 degreesor less. In addition, “vertical” refers to a state in which two straightlines form an angle between 80 degrees and 100 degrees and thus,includes a state in which the angle is between 85 and 95 degrees.

In the present disclosure, a “film” and a “layer” are interchangeable.For example, sometimes “conductive layer” may be replaced by “conductivefilm”. Similarly, “insulating film” may sometimes be replaced by“insulating layer”.

The term “about” herein means that the limit is not strictly set, and avalue within the range of process and measurement errors is allowed.

FIG. 1 is a schematic structural diagram of an OLED display apparatus.As shown in FIG. 1, the OLED display apparatus may include a scanningsignal driver, a data signal driver, a light-emitting signal driver, anOLED display panel, a first power supply unit, a second power supplyunit and an initial power supply unit. In an exemplary embodiment, theOLED display substrate at least includes a plurality of scanning signallines (S1 to SN), a plurality of data signal lines (D1 to DM) and aplurality of light-emitting signal lines (EM1 to EMN). The scanningsignal driver is configured to sequentially supply scanning signals tothe plurality of scanning signal lines (S1 to SN), the data signaldriver is configured to supply data signals to the plurality of datasignal lines (D1 to DM), and the light-emitting signal driver isconfigured to sequentially supply light-emitting control signals to theplurality of light-emitting signal lines (EM1 to EMN). In an exemplaryembodiment, the plurality of scanning signal lines and the plurality oflight-emitting signal lines extend along a horizontal direction, and theplurality of data signal lines extend along a vertical direction. Thedisplay apparatus includes a plurality of sub-pixels, and one sub-pixelis connected with a scanning signal line, a light-emitting control lineand a data signal line, for example. The first power supply unit, thesecond power supply unit and the initial power supply unit areconfigured to supply a first power supply voltage, a second power supplyvoltage and an initial power supply voltage to a pixel circuit through afirst power supply line, a second power supply line and an initialsignal line, respectively.

FIG. 2 is a schematic plan view of a display area of a displaysubstrate. As shown in FIG. 2, the display area may include a pluralityof pixel units P arranged in a matrix, at least one of which includes afirst sub-pixel P1 emitting light of a first color, a second sub-pixelP2 emitting light of a second color, and a third sub-pixel P3 emittinglight of a third color. The first sub-pixel P1, the second sub-pixel P2,and the third sub-pixel P3 each include a pixel driving circuit and alight-emitting device. The pixel driving circuits in the first sub-pixelP1, the second sub-pixel P2, and the third sub-pixel P3 are respectivelyconnected with the scanning signal line, the data signal line and thelight-emitting signal line. The pixel driving circuit is configured toreceive a data voltage transmitted by the data signal line and output acorresponding current to the light-emitting device under a control ofthe scanning signal line and the light-emitting signal line. Thelight-emitting devices in the first sub-pixel P1, the second sub-pixelP2 and the third sub-pixel P3 are respectively connected with the pixeldriving circuits of the sub-pixels where the light-emitting devices arelocated. The light-emitting device is configured to emit light with acorresponding brightness in response to a current output by the pixeldriving circuit of the sub-pixel where the light-emitting device islocated.

In an exemplary embodiment, the pixel unit p may include red (R), green(G) and blue (B) sub-pixels, or may include red, green, blue and white(W) sub-pixels, which is not limited in the present disclosure. In anexemplary embodiment, a shape of the sub-pixel in the pixel unit may berectangular, diamond, pentagonal or hexagonal. When the pixel unitincludes three sub-pixels, the three sub-pixels may be arranged in amanner to stand side by side horizontally, in a manner to stand side byside vertically, or in a pyramid manner with two units sitting at thebottom and one unit placed on top. When the pixel unit includes foursub-pixels, the four sub-pixels may be arranged in a manner to standside by side horizontally, in a manner to stand side by side vertically,or in a manner to form a square, which is not specifically limited inthe present disclosure.

FIG. 3 is a schematic sectional view of a display substrate, showing astructure of three sub-pixels in an OLED display substrate. As shown inFIG. 3, on a plane perpendicular to the display substrate, the displaysubstrate may include a driving circuit layer 102 arranged on asubstrate 101, a light-emitting device 103 arranged on a side of thedriving circuit layer 102 away from the substrate 101, and anencapsulation layer 104 arranged on a side of the light-emitting device103 away from the substrate 101. In some possible implementations, thedisplay substrate may include other film layers, such as spacer posts,etc., which is not limited in the present disclosure.

In an exemplary implementation, the substrate may be a flexiblesubstrate or may be a rigid substrate. The flexible substrate mayinclude a first flexible material layer, a first inorganic materiallayer, a semiconductor layer, a second flexible material layer and asecond inorganic material layer which are stacked, wherein materials ofthe first flexible material layer and the second flexible material layermay be polyimide (PI), polyethylene terephthalate (PET) or a polymersoft film with surface treatment; materials of the first inorganicmaterial layer and the second inorganic material layer may be siliconnitride (SiNx) or silicon oxide (SiOx), etc., for improving thewater-resistance and oxygen-resistance of the substrate; and thematerial of the semiconductor layer may be amorphous silicon (a-si).

In an exemplary embodiment, the driving circuit layer 102 of eachsub-pixel may include a plurality of transistors and a storage capacitorconstituting a pixel driving circuit, an example of which is illustratedin FIG. 3 where each sub-pixel includes a driving transistor and astorage capacitor. In some possible implementations, the driving circuitlayer 102 of each sub-pixel may include: a first insulating layer 201arranged on the substrate; an active layer arranged on the firstinsulating layer; a second insulating layer 202 covering the activelayer; a gate electrode and a first capacitor electrode arranged on thesecond insulating layer 202; a third insulating layer 203 covering thegate electrode and the first capacitor electrode; a second capacitorelectrode arranged on the third insulating layer 203; a fourthinsulating layer 204 covering the second capacitor electrode, whereinthe second insulating layer 202, the third insulating layer 203 and thefourth insulating layer 204 are provided with via holes exposing theactive layer; a source electrode and a drain electrode arranged on thefourth insulating layer 204, wherein the source electrode and the drainelectrode are respectively connected with the active layer through viaholes; and a flat layer 205 covering the aforementioned structure,wherein the flat layer 205 is provided with a via hole exposing thedrain electrode. The active layer, the gate electrode, the sourceelectrode and the drain electrode constitute a driving transistor 210,and the first capacitor electrode and the second capacitor electrodeconstitute a storage capacitor 211.

In an exemplary embodiment, the light-emitting device 103 may include ananode 301, a pixel defining layer 302, an organic light-emitting layer303 and a cathode 304. The anode 301 is arranged on the flat layer 205,and is connected with the drain electrode of the driving transistor 210through a via hole formed in the flat layer 205. The pixel defininglayer 302 is arranged on the anode 301 and the flat layer 205, and thepixel defining layer 302 is provided with a pixel opening exposing theanode 301. The organic light-emitting layer 303 is at least partiallyarranged in the pixel opening, and the organic light-emitting layer 303is connected with the anode 301. The cathode 304 is arranged on theorganic light-emitting layer 303 and connected with the organiclight-emitting layer 303. The organic light-emitting layer 303 emitslight of a corresponding color driven by the anode 301 and the cathode304.

In an exemplary embodiment, the encapsulation layer 104 may include afirst encapsulation layer 401, a second encapsulation layer 402 and athird encapsulation layer 403 which are stacked. The first encapsulationlayer 401 and the third encapsulation layer 403 may be made of aninorganic material, and the second encapsulation layer 402 may be madeof an organic material. The second encapsulation layer 402 is arrangedbetween the first encapsulation layer 401 and the third encapsulationlayer 403 to ensure that external moisture is unable to enter thelight-emitting device 103.

In an exemplary embodiment, the organic light-emitting layer 303 may atleast include a hole injection layer 20, a hole transport layer 30, alight-emitting layer 50 and a hole block layer 60 which are stacked onthe anode 301. In an exemplary embodiment, the hole injection layer 20of all sub-pixels is a common layer connected together. The holetransport layer 30 of all sub-pixels is a common layer connectedtogether. The light-emitting layers 50 of adjacent sub-pixels mayoverlap in a small portion or be isolated. The hole block layer 60 is acommon layer connected together.

In an exemplary implementation, the pixel driving circuit may have astructure of 3T1C, 4T1C, 5T1C, 5T2C, 6T1C or 7T1C. FIG. 4 is anequivalent circuit diagram of a pixel driving circuit. As shown in FIG.4, the pixel driving circuit may include seven switching transistors (afirst transistor T1 to a seventh transistor T7), a storage capacitor Cand eight signal lines (a data signal line DATA, a first scanning signalline S1, a second scanning signal line S2, a first initial signal lineINIT1, a second initial signal line INIT2, a first power supply lineVSS, a second power supply line VDD and a light-emitting signal lineEM).

In an exemplary implementation, a control electrode of the firsttransistor T1 is connected with the second scanning signal line S2, afirst electrode of the first transistor T1 is connected with the firstinitial signal line INIT1, and a second electrode of the firsttransistor is connected with a second node N2. A control electrode ofthe second transistor T2 is connected with the first scanning signalline S1, a first electrode of the second transistor T2 is connected withthe second node N2, and a second electrode of the second transistor T2is connected with a third node N3. A control electrode of the thirdtransistor T3 is connected with the second node N2, a first electrode ofthe third transistor T3 is connected with the first node N1, and asecond electrode of the third transistor T3 is connected with the thirdnode N3. A control electrode of the fourth transistor T4 is connectedwith the first scanning signal line S 1, a first electrode of the fourthtransistor T4 is connected with the data signal line DATA, and a secondelectrode of the fourth transistor T4 is connected with the first nodeN1. A control electrode of the fifth transistor T5 is connected with thelight-emitting signal line EM, a first electrode of the fifth transistorT5 is connected with the second power supply line VDD, and a secondelectrode of the fifth transistor T5 is connected with the first nodeN1. A control electrode of the sixth transistor T6 is connected with thelight emitting signal line EM, a first electrode of the sixth transistorT6 is connected with the third node N3, and a second electrode of thesixth transistor T6 is connected with a first electrode of thelight-emitting device. A control electrode of the seventh transistor T7is connected with the first scanning signal line S1, a first electrodeof the seventh transistor T7 is connected with the second initial signalline INIT2, and a second electrode of the seventh transistor T7 isconnected with the first electrode of the light-emitting device. A firstend of the storage capacitor C is connected with the second power supplyline VDD, and a second end of the storage capacitor C is connected withthe second node N2.

In an exemplary implementation, the first transistor T1 to the seventhtransistor T7 may be P-type transistors or may be N-type transistors.Adopting transistors of the same type in the pixel driving circuit maysimplify a process flow, reduce difficulty in a preparation process ofthe display panel, and improve a product yield rate. In some possibleimplementations, the first transistor T1 to the seventh transistor T7may include P-type transistors and N-type transistors.

In an exemplary implementation, a second electrode of the light-emittingdevice is connected with the first power supply line VSS. A signal onthe first power supply line VSS is a low level signal, and a signal onthe second power supply line VDD is a high level signal that iscontinuously supplied. The first scanning signal line S1 is a scanningsignal line for a pixel driving circuit of a current display row, andthe second scanning signal line S2 is a scanning signal line for a pixeldriving circuit of a previous display row. That is, for an nth displayrow, the first scanning signal line S1 is S(n), the second scanningsignal line S2 is S(n-1), the second scanning signal line S2 of thecurrent display row and the first scanning signal line S1 for the pixeldriving circuit of the previous display row are the same signal line,which may reduce the signal lines of the display panel and realize thenarrow frame of the display panel.

In an exemplary embodiment, the organic light-emitting layer of the OLEDlight-emitting element may include an Emitting Layer (EML), and one ormore film layers selected from a Hole Injection Layer (HIL), a HoleTransport Layer (HTL), a Hole Block Layer (HBL), an Electron Block Layer(EBL), an Electron Injection Layer (EIL) and an Electron Transport Layer(ETL). Driven by the voltage of the anode and the cathode, light isemitted using the light-emitting characteristics of the organic materialaccording to the required gray scale.

In an exemplary embodiment, the light-emitting layers of OLEDlight-emitting elements of different colors are different. For example,red light-emitting element includes a red light-emitting layer, greenlight-emitting element includes a green light-emitting layer, and bluelight-emitting element includes a blue light-emitting layer. In order toreduce the process difficulty and improve the yield, a common layer maybe used for the hole injection layer and the hole transport layer on oneside of the light-emitting layer, and a common layer may be used for theelectron injection layer and the electron transport layer on the otherside of the light-emitting layer. In an exemplary embodiment, any one ormore layers of the hole injection layer, the hole transport layer, theelectron injection layer and the electron transport layer may bemanufactured by one-time process (one-time evaporation process orone-time ink-jet printing process), but the isolation is realized bymeans of the height difference of formed film layer or by means of thesurface treatment. For example, any one or more layers of the holeinjection layer, the hole transport layer, the electron injection layerand the electron transport layer corresponding to adjacent sub-pixelsmay be isolated. In an exemplary embodiment, the organic light-emittinglayer may be formed by evaporation using a Fine Metal Mask (FMM) or anOpen Mask, or by ink jet process.

In an OLED structure, the material for the hole injection layer HIL issimilar to that for the hole transport layer HTL. The Highest OccupiedMolecular Orbit (HOMO) energy level of the material of the holeinjection layer is between the anode work function and the HOMO energylevel of the material of the hole transport layer, so that the holeinjection may be achieved by reducing the potential barrier between theanode and the hole transport layer. Studies have shown that potentialbarriers still exist between the layers of the structure, and theinjection effect is poor.

In another OLED structure, the hole injection layer adopts a dopedstructure, which includes a host material and a doping material. Thedoped material is a P-doping material, such as2,3,5,6-tetrafluoro-7,7′,8,8′-tetracyandimethyl (F4-TCNQ). The hostmaterial and the doping material are doped according to a certainproportion to form a doped structure. P-doping material is a kind ofmaterial with strong electron-withdrawing ability, which lacks electronsand has strong ability to withdraw electrons. Therefore, due to thestrong electron-withdrawing ability of the P-doping material, electronsmove rapidly toward the anode under the action of electric field, andholes are rapidly transported toward the hole transport layer, thusachieving better hole injection performance. Studies have shown that thep-type doped structure has poor thermal stability and is easy tocrystallize, which is not conducive to the preparation. When the dopingratio is greater than 5%, it is easy to cause crosstalk betweensub-pixels, resulting in poor display.

In another OLED structure, the hole injection layer is made of amaterial with strong electron-withdrawing property, which can not onlyimprove the hole injection performance, but also improve the poordisplay caused by P-type doping. Studies have shown that materials withthis property usually have strong molecular polarity, are easy tocrystallize, have poor stability and are difficult to process.

An Exemplary embodiment of the present disclosure provides an organiclight emitting device, including an anode, a cathode, and alight-emitting layer arranged between the anode and the cathode. Thedoped structure layer includes a host material and a guest materialdoped in the host material. The host material and the guest materialsatisfy:

−1.5eV<|LUMO(A)|−|HOMO(B)|<1.5eV.

LUMO(A) is the lowest unoccupied molecular orbit (LUMO) energy level ofthe host material, and HOMO(B) is the highest occupied molecular orbit(HOMO) energy level of the guest material.

In an exemplary embodiment, the doping ratio of the guest material tothe doped structure layer is 0.1% to 40%.

In an exemplary embodiment, one of the host material and the guestmaterial includes a ketone compound and the other includes an aromaticamine compound. For example, the host material includes a ketonecompound, and the guest material includes an aromatic amine compound.

In an exemplary embodiment, the doped structure layer includes a holeinjection layer.

In an exemplary embodiment, a thickness of the hole injection layer is 1nm to 10 nm.

FIG. 5 is a schematic diagram of an OLED structure according to anexemplary embodiment of the present disclosure. As shown in FIG. 5, theOLED includes an anode 10, a cathode 90, and an organic light-emittinglay arranged between the anode 10 and the cathode 90. In an exemplaryembodiment, the organic light-emitting layer includes a hole injectionlayer 20, a hole transport layer 30, an electron block layer 40, alight-emitting layer 50, a hole block layer 60, an electron transportlayer 70 and an electron injection layer 80 which are stacked. The holeinjection layer 20 is configured to lower the potential barrier forinjecting holes from the anode, so that the holes may be efficientlyinjected into the light-emitting layer 50 from the anode. The holetransport layer 30 is configured to realize directional and orderlycontrolled migration of injected holes. The electron block layer 40 isconfigured to form a migration barrier for electrons and preventelectrons from migrating out of the light-emitting layer 50. Thelight-emitting layer 50 is configured to recombine electrons and holesto emit light. The hole block layer 60 is configured to form a migrationbarrier for holes and prevent holes from migrating out of thelight-emitting layer 50. The electron transport layer 70 is configuredto realize directional and orderly controlled migration of injectedelectrons. The electron injection layer 80 is configured to lower thepotential barrier of electrons injected from the cathode, so thatelectrons may be efficiently injected from the cathode into thelight-emitting layer 50.

In an exemplary embodiment, the doped structure layer is a holeinjection layer 20, which includes a host material A and a guestmaterial B doped in the host material A. The highest occupied molecularorbit (HOMO) energy level and the Lowest Unoccupied Molecular Orbit(LUMO) energy level of the host material A and the guest material Bsatisfy:

−1.5eV<|LUMO(A)|−|HOMO(B)|<1.5eV.

LUMO(A) is the lowest unoccupied molecular orbit (LUMO) energy level ofthe host material A, and HOMO(B) is the highest occupied molecular orbit(HOMO) energy level of the guest material B.

In an exemplary embodiment, the HOMO energy level and the LUMO energylevel of the host material A satisfy:

|HOMO(A)|≥6eV,|LUMO(A)|≥4eV.

HOMO(A) is the highest occupied molecular orbit (HOMO) energy level ofthe host material A.

In an exemplary embodiment, the HOMO energy level of the guest materialB satisfies:

5eV≤|HOMO(B)|≤6.5eV.

In an exemplary embodiment, |LUMO(A)| may be greater than or equal to|HOMO(B)|, or |LUMO(A)| may be less than or equal to |HOMO(B)|.

In an exemplary embodiment, the host material A and the guest material Bmay be evaporated together by a multi-source evaporation process to forma hole injection layer with a doped structure.

In an exemplary embodiment, the doping ratio of the guest material B tothe hole injection layer is about 0.1% to 40%. In an exemplaryembodiment of the present disclosure, the doping ratio refers to theratio of the mass of the guest material to the mass of the holeinjection layer, that is, the mass percentage. In an exemplaryembodiment, the host material and the guest material are co-evaporated,so that the host material and the guest material are uniformly dispersedin the hole injection layer. The doping ratio may be controlled bycontrolling the evaporation rate of the guest material or by controllingthe evaporation rate ratio of the host material to the guest material.

In some possible implementations, the doping ratio of the guest materialB to the hole injection layer may be about 0.5% to 30%.

In some possible implementations, the doping ratio of the guest materialB to the hole injection layer may be about 5% to 20%.

In some possible implementations, the doping ratio of the guest materialB to the hole injection layer may be about 0.5% to 10%.

In some possible implementations, the doping ratio of the guest materialB to the hole injection layer may be about 5% to 10%.

In an exemplary embodiment, a thickness of the hole injection layer 20is about 1 nm to 10 nm. Since the guest material is doped in the hostmaterial, it will affect the properties of the host material to acertain extent. Too thick film will lead to a decrease in service life,while too thin film will affect the film forming property anduniformity, thereby leading to the discontinuity of the film andaffecting the injection performance.

In an exemplary embodiment, the guest material B may be made of anaromatic amine compound. Aromatic amine compound is a kind of holetransport material that has high mobility and high stability and isdifficult to crystallize.

In an exemplary embodiment, the guest material B includes but is notlimited to the structure shown in formula (I):

In formula (I), L is a connecting group formed by a substituted orunsubstituted arylene group having 5 to 50 ring atoms, or a connectinggroup obtained by connecting a plurality of substituted or unsubstitutedarylene groups having 5 to 50 ring atoms with M1, wherein M1 is any oneof single bond, oxygen atom, sulfur atom, nitrogen atom, and saturatedor unsaturated divalent aliphatic hydrocarbon group having 1 to 20carbon atoms.

In formula (I), Ar1 to Ar4 may not be completely the same, and are eachindependently a substituted or unsubstituted aryl having 5 to 50 ringatoms, and at least one of Ar1 to Ar4 is selected from any one of thefollowing structures:

R1 to R25 are each independently any one of:

hydrogen atom, aryl group having 5 to 50 ring atoms, substituted orunsubstituted alkyl group having 1 to 50 carbon atoms, substituted orunsubstituted alkoxy group having 1 to 50 carbon atoms, substituted orunsubstituted aralkyl group having 6 to 50 ring atoms, substituted orunsubstituted aryloxy group having 5 to 50 ring atoms, substituted orunsubstituted arylthio group having 5 to 50 ring atoms, substituted orunsubstituted alkoxycarbonyl group having 1 to 50 carbon atoms, and arylgroup having 5 to 50 ring atoms substituted by M2, wherein M2 is amino,halogen atom, cyano, nitro, hydroxyl or carboxyl.

In an exemplary embodiment, the main material A is made of a ketonecompound. The ketone compound is a hole injection material with strongelectron-withdrawing ability. The strong electron-withdrawing ability isshown as having good electron affinity, which is characterized by HOMOenergy level and LUMO energy level.

In an exemplary embodiment, the host material A includes but is notlimited to the structure shown in formula (II):

In formula (II), Z may be a substituted or unsubstituted benzene ring,pyridine ring, thiophene ring, quinoline, indole or thienothiophenering.

Y₁ to Y₄ may each independently be N or C-R35. Y₁ to Y₄ may be the sameas each other or may be different from each other.

In an exemplary embodiment, R31 to R34 may be the same as or differentfrom each other, and are each independently any one of hydrogen,deuterium, halogen group, nitrile group, substituted or unsubstitutedalkyl group, substituted or unsubstituted haloalkyl group, substitutedor unsubstituted alkoxy group, substituted or unsubstituted haloalkoxygroup, substituted or unsubstituted aryl group, substituted orunsubstituted halogenated aryl group, substituted or unsubstituted silylgroup and substituted or unsubstituted heterocycle.

In an exemplary embodiment, R35 may be any one of hydrogen, deuterium,halogen group, nitrile group, substituted or unsubstituted alkyl group,substituted or unsubstituted haloalkyl group, substituted orunsubstituted alkoxy group, substituted or unsubstituted haloalkoxygroup, substituted or unsubstituted aryl group, substituted orunsubstituted halogenated aryl group, substituted or unsubstituted silylgroup and substituted or unsubstituted heterocycle.

In an exemplary embodiment, Ar₅ in formula (II) may be:

In an exemplary embodiment, Ar₆ in formula (II) may be:

In an exemplary embodiment, X1 and X2 in Ar₅ and Ar₆ may be the same ormay be different.

In an exemplary embodiment, X1 and X2 may each be independently selectedfrom any one of the following structures:

In an exemplary embodiment, R41 to R43 are each hydrogen, fluoroalkyl,alkyl, aryl or heterocyclic group, and R42 and R43 may form a ring.

In an exemplary embodiment, the anode may be made of a material having ahigh work function. For the bottom emission type, the anode may be madeof a transparent oxide material, such as indium tin oxide (ITO) orindium zinc oxide (IZO), and the thickness of the anode may be about 80nm to 200 nm. For the top emission type, the anode may be made of acomposite structure of metal and transparent oxide, such as Ag/ITO,Ag/IZO or ITO/Ag/ITO. The thickness of the metal layer in the anode maybe about 80 nm to 100 nm, and the thickness of the transparent oxide inthe anode may be about 5 nm to 20 nm, so that the average reflectivityof the anode in the visible region is about 85%-95%.

In an exemplary embodiment, for the top emission OLED, the cathode maybe formed by an evaporation process using a metal material. The metalmaterial may be magnesium (Mg), silver (Ag) or aluminum (Al), or alloymaterial such as Mg:Ag alloy, with the ratio of Mg:Ag being about 3:7 to1:9. The thickness of the cathode may be about 10 nm to 20 nm sch thatthe average transmittance of the cathode at a wavelength of 530 nm isabout 50%˜60%. For the bottom emission OLED, the cathode may be made ofmagnesium (Mg), silver (Ag), aluminum (Al) or Mg:Ag alloy. The thicknessof the cathode may be greater than about 80 nm, so that the cathode 90has good reflectivity.

In an exemplary embodiment, at least one organic layer is furtherarranged between the hole injection layer and the light-emitting layer,and the at least one organic layer may be a hole transport layer. In anexemplary embodiment, the hole transport layer may be formed by anevaporation process using a material with high hole mobility, such ascarbazole, methylfluorene, spirofluorene, dibenzothiophene or furan. Thethickness of the hole transport layer may be about 90 nm to 140 nm, thecarrier mobility of the hole transport layer may be about 10⁻³ cm²/Vs to10⁻⁵ cm²/Vs, and the conductivity of the hole transport layer is lessthan or equal to that of the hole injection layer.

In an exemplary embodiment, the material of the hole transport layer maybe the same as the guest material B in the hole injection layer.

In an exemplary embodiment, the HOMO energy level of the material of thehole transport layer satisfies:

5eV≤|HOMO(D)|≤6.5eV.

HOMO(D) is the highest occupied molecular orbit (HOMO) energy level ofthe hole transport layer.

In an exemplary embodiment, two organic layers are further arrangedbetween the hole injection layer and the light-emitting layer. The twoorganic layers may be a hole transport layer and an electron blocklayer. In an exemplary embodiment, the electron block layer may have athickness of about 1 nm to 10 nm, and is configured to transfer holesand block electrons and block excitons generated in the light-emittinglayer. The conductivity of the electron block layer is less than orequal to that of the hole injection layer.

In an exemplary embodiment, the light-emitting layer may include alight-emitting host material and a light-emitting guest material. Thelight-emitting host material may be a bipolar single host, or may be adouble host formed by blending a hole-type host and an electron-typehost. The light-emitting guest material may be a phosphorescentmaterial, a fluorescent material, a delayed fluorescent material and thelike. The doping ratio of the light-emitting guest material is about 5%to 15%.

In an exemplary embodiment, the hole block layer has a thickness ofabout 2 nm to 10 nm and is configured to block holes and excitonsgenerated in the light-emitting layer.

In an exemplary embodiment, the electron transport layer may be made ofthiophene, imidazole or azine derivatives by blending with lithiumquinoline. The doping ratio of lithium quinoline to the electrontransport layer is about 30% to 70%, and the thickness of the electrontransport layer may be about 20 nm to 70 nm.

In an exemplary embodiment, the electron injection layer may be formedby an evaporation process using materials such as lithium fluoride(LiF), lithium 8-hydroxyquinoline (LiQ), ytterbium (Yb) or Calcium (ca),and the thickness of the electron injection layer may be about 0.5 nm to2 nm.

In an exemplary embodiment, the OLED may include an encapsulation layer,which may be encapsulated by frame glue or by thin film.

In an exemplary embodiment, for the top emission OLED, the thickness ofthe organic light-emitting layer between the anode and the cathode maybe designed to meet the optical path requirements of the opticalmicroresonator, so as to obtain the optimal intensity and color of theemitted light.

In an exemplary embodiment, a display substrate including an OLEDstructure may be formed in the following manner. A driving circuit layeris formed on a substrate through a patterning process, and the drivingcircuit layer of each sub-pixel may include a driving transistor and astorage capacitor constituting a pixel driving circuit. A flat layer isformed on the substrate on which the aforementioned structure is formed,and a via hole exposing a drain electrode of the driving transistor isformed on a flat layer of each sub-pixel. An anode is formed by apatterning process on the substrate on which the aforementionedstructure is formed, and the anode of each sub-pixel is connected withthe drain electrode of the driving transistor through the via hole onthe flat layer. A pixel defining layer is formed by a patterning processon the substrate on which the aforementioned structure is formed, apixel opening exposing the anode is formed on the pixel defining layerof each sub-pixel, and each pixel opening serves as a light-emittingarea of each sub-pixel. On the substrate on which the aforementionedstructure is formed, firstly, an open mask is used to evaporate a holeinjection layer, a hole transport layer and an electron block layer insequence to form a common layer of the hole injection layer, the holetransport layer and the electron block layer on the display substrate.That is, the hole injection layers of all sub-pixels are communicated,the hole transport layers of all sub-pixels are communicated and theelectron block layers of all sub-pixels are communicated. For example,the first hole injection layer, the second hole injection layer, thehole transport layer and the electron block layer have approximately thesame area but different thicknesses. Then, a fine metal mask is used toevaporate the red, green and blue light-emitting layers in differentsub-pixels, and the light-emitting layers of adjacent sub-pixels mayoverlap in a small portion (for example, the overlapping portionaccounts for less than 10% of the area of the pattern of the respectivelight-emitting layer), or they may be isolated. Then, a fine metal maskis used to evaporate red, green and blue light-emitting layers indifferent sub-pixels, and the light-emitting layers of adjacentsub-pixels are isolated. Then, an open mask is used to evaporate thehole block layer, the electron transport layer, the electron injectionlayer and the cathode in sequence to form a common layer of the holeblock layer, the electron transport layer, the electron injection layerand the cathode on the display substrate. That is, the hole block layersof all sub-pixels are communicated, the electron transport layers of allsub-pixels are communicated, and the cathodes of all sub-pixels arecommunicated.

In an exemplary embodiment, the orthographic projection of one or moreof the first hole injection layer, the second hole injection layer, thehole transport layer, the electron block layer, the hole transportlayer, the electron injection layer and the cathode on the substrate iscontinuous. In some examples, at least one of the first hole injectionlayer, the second hole injection layer, the hole transport layer, theelectron block layer, the hole block layer, the electron transportlayer, the electron injection layer and the cathode of at least one rowor column of the sub-pixels are communicated. In some examples, at leastone of the first hole injection layer, the second hole injection layer,the hole transport layer, the electron block layer, the hole blocklayer, the electron transport layer, the electron injection layer andthe cathode of a plurality of sub-pixels are communicated.

In an exemplary embodiment, the organic light-emitting layer may includea microcavity adjusting layer located between the hole transport layerand the light-emitting layer. For example, after the hole transportlayer is formed, a fine metal mask may be used to evaporate the redmicrocavity adjusting layer and the red light-emitting layer, the greenmicrocavity adjusting layer and the green light-emitting layer, and theblue microcavity adjusting layer and the blue light-emitting layer indifferent sub-pixels.

In an exemplary embodiment, since the hole injection layer is a commonlayer, the area of the hole injection layer may be approximately thesame, and the orthographic projection of the hole injection layer on thesubstrate at least includes the orthographic projection of thelight-emitting areas of two sub-pixels. That is, the orthographicprojection of the hole injection layer on the substrate overlaps withthe orthographic projection of the light-emitting areas of at least twosub-pixels.

In an exemplary embodiment, since the hole injection layer is a commonlayer and the light-emitting layers of different sub-pixels areisolated, the orthographic projection of the hole injection layer on thesubstrate includes the orthographic projection of the light-emittinglayer on the substrate, and the area of the hole injection layer islarger than that of the light-emitting layer.

In an exemplary embodiment, the orthographic projection of thelight-emitting layer of at least part of the sub-pixels on the substrateoverlaps with the orthographic projection of the driving transistor ofthe pixel driving circuit on the substrate.

Table 1 shows the performance comparison results of different structuresof hole injection layer in OLED. The three comparative structures alladopt the structure shown in FIG. 5, the anode is made of ITO and thecathode is made of Mg:Ag alloy. The hole injection layer of structure 1is a 3% P-type doped structure. The hole injection layer of structure 2is an undoped structure, including a single host material A. The holeinjection layer of structure 3 is a doped structure according to anexemplary embodiment of the present disclosure, which includes hostmaterial A and guest material B. LT95 in Table 1 indicates the time forOLED to decrease from initial brightness (100%) to 95% brightness. Sincethe life curve follows the multi-exponential decay model, the life ofOLED may be estimated according to LT95. As shown in Table 1, comparedwith Structure 1 and Structure 2, Structure 3 has obvious improvement inprolonging the service life, indicating that the hole injection layerwith doped structure proposed in the exemplary embodiment of the presentdisclosure may optimize the crystallinity and stability of materials andimprove the service life of devices.

TABLE 1 Performance comparison of different structures of hole injectionlayer Current Comparative density Chromaticity structure (mA/cm²)Voltage Efficiency coordinate LT95 Structure 1 15. 100%  100% (0.135,0.055) 100% Device 2 99% 102% (0.139, 0.047)  91% Device 3 98% 100%(0.140, 0.046) 118%

Table 2 shows the performance comparison results of hole injection layerwith different doping ratios in OLED. The three comparative structuresall adopt the structure shown in FIG. 5, the anode is made of ITO andthe cathode is made of Mg:Ag alloy. The hole injection layer is thedoped structure of according to an exemplary embodiment of the presentdisclosure, which includes host material A and guest material B. Thedoping ratio of guest material B in structure 4 is 5%, that in structure5 is 10%, and that in structure 6 is 30%. As shown in Table 2, comparedwith the hole injection layer made of a single material (Structure 2 inTable 1), different doping ratios may effectively prolong the servicelife. When the doping ratio of guest material B is 5% and 10%, thevoltage and efficiency of the hole injection layer have little change,but the service life is obviously improved, indicating that the dopingratio greater than 5% will not lead to cross-talk between sub-pixels,thus effectively avoiding the problem of low doping ratio of P-typedoped structure. When the doping ratio of guest material B is equal to30%, the service life is increased greatly, but the voltage increasesand the efficiency decreases.

TABLE 2 Performance comparison of hole injection layer with differentdoping ratios Current Comparative doping ratio of density structure B inHIL layer (mA/cm²) Voltage Efficiency LT95 Structure 4  5% 10 104% 98%117% Structure 5 10% 103% 101%  112% Structure 6 30% 112% 89% 123%

Table 3 is another comparison result of OLED according to an exemplaryembodiment of the present disclosure. The three comparative structuresall adopt the structure shown in FIG. 5, the anode is made of ITO andthe cathode is made of Mg:Ag alloy. The hole injection layer is thedoped structure of according to an exemplary embodiment of the presentdisclosure, which includes host material A and guest material B. Thethickness of the hole injection layer in structure 7 is 1 nm, that instructure 8 is 5 nm, and that in structure 9 is 10 nm. As shown in Table3, when the thickness of the hole injection layer is 5 nm, the voltagedecreases slightly and the efficiency increases slightly. When thethickness of the hole injection layer is 10 nm, the voltage increasesslightly and the efficiency decreases slightly. From the general trend,with the increase in the thickness of the hole injection layer, thevoltage and efficiency have no obvious change, but the service life hasa certain downward trend. Therefore, a proper thickness of the holeinjection layer may be selected according to the collocation ofstructural layers of the device.

TABLE 3 Performance comparison of hole injection layer with differentthicknesses Current Comparative Thickness of density structure HIL layer(nm) (mA/cm²) Voltage Efficiency LT95 Structure 7 1 10 100% 100% 100% Structure 8 5  97% 101% 94% Structure 9 10 102%  99% 77%

FIG. 6 is an SEM image of an evaporation film layer of a hole injectionlayer with an undoped structure; and FIG. 7 is an SEM image of anevaporation film layer of a hole injection layer according to anexemplary embodiment of the present disclosure. It can be seen from thescanning electron microscope (SEM) images in FIG. 6 and FIG. 7 that thehole injection layer of a single material (undoped structure) is fluffy,while the hole injection layer according to the exemplary embodiment ofthe present disclosure is denser and smoother, indicating that theoptimized doping structure according to the exemplary embodiment of thepresent disclosure improves the crystallinity and stability of the holeinjection layer. The fluffy film layer shown in FIG. 6 may easily causethe blocking phenomenon in the evaporation process, which leads toabnormal sensor activity value in the evaporation equipment, thuscausing shutdown of the equipment alarm. The exemplary embodiment of thepresent disclosure may effectively improve this phenomenon.

An exemplary embodiment of the present disclosure provides an OLED. Thehole injection layer adopts a doped structure different from P-typedoping, which may effectively improve the crystallinity and thermalstability of the hole injection material, reduce poor evaporationprocess, realize stable injection performance, effectively reduce thedevice voltage, and improve the efficiency and service life of thedevice. Since the doping material is different from the P-dopingmaterial, the problem of low doping ratio of the P-type doping structureis avoided, and the larger doping ratio (more than 5%) will not causecrosstalk between sub-pixels, thus effectively improving the displayquality. The hole injection layer provided by the exemplary embodimentof the present disclosure has good compatibility in the preparationprocess, does not increase the evaporation cavity, and can be massproduced.

The present disclosure further provides a display apparatus includingthe aforementioned organic light emitting device. The display apparatusmay be any product or component with a display function such as a mobilephone, a tablet computer, a television, a display, a notebook computer,a digital photo frame, a navigator, a vehicle display, a watch, abracelets, etc.

Although the embodiments disclosed in the present disclosure are asdescribed above, the described contents are only the embodiments forfacilitating understanding of the present disclosure, which are notintended to limit the present disclosure. Any person skilled in thefield to which the present application pertains can make anymodifications and variations in the forms and details of implementationwithout departing from the spirit and the scope disclosed in the presentapplication, but the patent protection scope of the present applicationshould still be subject to the scope defined by the appended claims.

What is claimed is:
 1. An organic light emitting device, comprising ananode, a cathode and a light-emitting layer arranged between the anodeand the cathode, wherein a doped structure layer is arranged between theanode and the light-emitting layer, the doped structure layer comprisesa host material and a guest material doped in the host material, and thehost material and the guest material satisfy:−1.5eV<|LUMO(A)|−|HOMO(B)|<1.5eV; where LUMO(A) is the lowest unoccupiedmolecular orbit (LUMO) energy level of the host material, and HOMO(B) isthe highest occupied molecular orbit (HOMO) energy level of the guestmaterial.
 2. The organic light emitting device according to claim 1,wherein the guest material further satisfies:5eV≤|HOMO(B)|≤6.5eV.
 3. The organic light emitting device according toclaim 1, wherein the host material further satisfies:|HOMO(A)|≥6eV,|LUMO(A)|≥4eV; where HOMO(A) is the highest occupiedmolecular orbit (HOMO) energy level of the host material.
 4. The organiclight emitting device according to claim 1, wherein a doping ratio ofthe guest material to the doped structure layer is 0.1% to 40%.
 5. Theorganic light emitting device according to claim 1, wherein one of thehost material and the guest material comprises a ketone compound and theother comprises an aromatic amine compound.
 6. The organic lightemitting device according to claim 1, wherein the guest materialcomprises but is not limited to a compound having a structure of formula(I):

in formula (I), Ar₁ to Ar₄ are each independently a substituted orunsubstituted aryl group having 5 to 50 ring atoms, L is a connectinggroup formed by a substituted or unsubstituted arylene group having 5 to50 ring atoms, or a connecting group obtained by connecting a pluralityof substituted or unsubstituted arylene groups having 5 to 50 ring atomswith M1, wherein M1 is any one of single bond, oxygen atom, sulfur atom,nitrogen atom, and saturated or unsaturated divalent aliphatichydrocarbon group having 1 to 20 carbon atoms.
 7. The organic lightemitting device according to claim 6, wherein at least one of Ar₁ to Ar₄is selected from any one of the following structures:

where R1 to R25 are each independently any one of hydrogen atom, arylgroup having 5 to 50 ring atoms, substituted or unsubstituted alkylgroup having 1 to 50 carbon atoms, substituted or unsubstituted alkoxygroup having 1 to 50 carbon atoms, substituted or unsubstituted aralkylgroup having 6 to 50 ring atoms, substituted or unsubstituted aryloxygroup having 5 to 50 ring atoms, substituted or unsubstituted arylthiogroup having 5 to 50 ring atoms, substituted or unsubstitutedalkoxycarbonyl group having 1 to 50 carbon atoms, and aryl group having5 to 50 ring atoms substituted by M2, wherein M2 is amino, halogen atom,cyano, nitro, hydroxyl or carboxyl.
 8. The organic light emitting deviceaccording to claim 1, wherein the host material comprises but is notlimited to a compound having a structure of formula (II):

in formula (II), Z is a substituted or unsubstituted benzene ring,pyridine ring, thiophene ring, quinoline, indole or thienothiophenering; Ar₅ is

Ar₆ is

Y₁ to Y₄ are each independently N or C-R35; R31 to R35 are eachindependently selected from any one of hydrogen, deuterium, halogengroup, nitrile group, substituted or unsubstituted alkyl group,substituted or unsubstituted haloalkyl group, substituted orunsubstituted alkoxy group, substituted or unsubstituted haloalkoxygroup, substituted or unsubstituted aryl group, substituted orunsubstituted halogenated aryl group, substituted or unsubstituted silylgroup and substituted or unsubstituted heterocycle; X1 and X2 are eachindependently selected from any one of the following structures:

R41 to R43 are each independently any one of hydrogen, fluoroalkyl,alkyl, aryl and heterocyclic group, and R42 and R43 form a ring.
 9. Theorganic light emitting device according to claim 1, wherein the dopedstructure layer comprises a hole injection layer.
 10. The organic lightemitting device according to claim 9, wherein the hole injection layerhas a thickness of 1 nm to 10 nm.
 11. The organic light emitting deviceaccording to claim 9, wherein at least one organic layer is furtherarranged between the hole injection layer and the light-emitting layer,a carrier mobility in the at least one organic layer is 10⁻³ cm²/Vs to10⁻⁵ cm²/Vs, and/or a conductivity of the at least one organic layer isless than or equal to that of the hole injection layer.
 12. The organiclight emitting device according to claim 11, wherein a material of theat least one organic layer is the same as that of the guest material.13. The organic light emitting device according to claim 11, wherein theat least one organic layer is a hole transport layer, and a material ofthe hole transport layer satisfies:5eV≤|HOMO(D)|≤6.5eV; where HOMO(D) is the highest occupied molecularorbit (HOMO) energy level of the hole transport layer.
 14. The organiclight emitting device according to claim 11, wherein two organic layersare further arranged between the hole injection layer and thelight-emitting layer, and a carrier mobility in the two organic layersis 10⁻³ cm²/Vs to 10⁻⁵ cm²/Vs, and/or a conductivity of the two organiclayers is less than or equal to that of the hole injection layer.
 15. Adisplay apparatus comprising the organic light emitting device accordingto claim
 1. 16. The display apparatus according to claim 15, comprisinga substrate and a plurality of sub-pixels formed on the substrate,wherein the sub-pixels include the organic light emitting device, and anorthographic projection of the hole injection layer on the substrateoverlaps with that of a light-emitting area of at least two sub-pixelson the substrate.
 17. The display apparatus according to claim 16,wherein an area of the hole injection layer is larger than that of thelight-emitting layer.
 18. The display apparatus according to claim 16,wherein the sub-pixel further comprises a pixel driving circuit, and theorthographic projection of the light-emitting layer of at least part ofthe sub-pixels on the substrate overlaps with an orthographic projectionof a driving transistor of the pixel driving circuit on the substrate.19. The organic light emitting device according to claim 2, wherein theguest material comprises but is not limited to a compound having astructure of formula (I):

in formula (I), Ar₁ to An are each independently a substituted orunsubstituted aryl group having 5 to 50 ring atoms, L is a connectinggroup formed by a substituted or unsubstituted arylene group having 5 to50 ring atoms, or a connecting group obtained by connecting a pluralityof substituted or unsubstituted arylene groups having 5 to 50 ring atomswith M1, wherein M1 is any one of single bond, oxygen atom, sulfur atom,nitrogen atom, and saturated or unsaturated divalent aliphatichydrocarbon group having 1 to 20 carbon atoms.
 20. The organic lightemitting device according to claim 2, wherein the doped structure layercomprises a hole injection layer.